Posted on Vimeo by one of the hackers known as Starbug, the video takes us through the entire process from the initial scan to the actual fingerprint trickery.
The hacker scans an iPhone 5S that already has someone's fingerprint.
He then tweaks the scan to perfect the image of the fingerprint.
The scan is printed to paper and then to a circuit board, which
undergoes a chemical bath. A dummy print eventually emerges, which is
used to fool the security of the Touch ID, thus giving the hacker entry
into the iPhone.

Starbug told Ars Technica that the hack posed no challenge.
He said he expected the process to take a week or two. Instead, it
chewed up around 30 hours from start to finish. With better preparation,
he claims it would've taken only half an hour.
Despite Starbug's boasts, the procedure shown in the video seems
exact and intricate, requiring manipulated scans, chemical baths, and
printed circuit boards. And through it all, the hacker would need to
hang onto your iPhone 5S. A process that can mimic your fingerprint
certainly raises alarm bells, but this particular hack isn't something
your average iPhone thief would be able to pull off.